The Proper Procedures for Troubleshooting Mechanical Unit Injectors (MUI){1251, 1264, 1280, 1288, 1290} Caterpillar

Asphalt Paver:

AP-1000 (S/N: 1HD1-UP)

AP-1050 (S/N: 1JG1-UP)

BG-245B (S/N: 3XL1-UP)

Backhoe Loader:

446 (S/N: 6XF1-UP)

446B (S/N: 5BL1-UP)

Combine:

Lexion 450 (S/N: 6JK1-UP)

Marine Engine:

3116 (S/N: 1SK1-UP)

Excavator:

205B (S/N: 5ZF1-UP)

211B (S/N: 6XG1-UP)

213B (S/N: 1EJ1-UP)

214B (S/N: 4CF1-UP; 9MF1-UP)

215D (S/N: 9TF1-UP)

224B (S/N: 7WF1-UP)

312B (S/N: 9NW1-UP)

320B (S/N: 5BR1-UP)

325L (S/N: 2JK1-UP)

E110B (S/N: 8MF1-UP; 4FJ1-UP)

E120B (S/N: 6JF1-UP; 4XK1-UP)

E180 (S/N: 1RF1-UP)

E200B (S/N: 6KF1-UP; 6KG1-UP)

E240B (S/N: 8SF1-UP; 9PF1-UP; 6MG1-UP)

E240C (S/N: 2RL1-UP)

EL180 (S/N: 4EF1-UP)

EL200B (S/N: 7DF1-UP)

EL240B (S/N: 5WG1-UP)

EL240C (S/N: 9PK1-UP)

M315 (S/N: 7ML1-UP)

Integrated Toolcarrier:

IT12F (S/N: 1KF1-UP)

IT14B (S/N: 3NJ1-UP)

IT14F (S/N: 4EL1-UP)

IT18B (S/N: 4ZD1-UP)

Off-Highway Truck/Tractor:

776B (S/N: 6JC1-UP)

777B (S/N: 4YC1-UP)

785 (S/N: 8GB1-UP)

789 (S/N: 9ZC1-UP)

793 (S/N: 3SJ1-UP)

Paving Compactor:

CB-434 (S/N: 3TF1-UP)

CP-563 (S/N: 1YJ1-UP)

CS-533 (S/N: 3BL1-UP; 4HL1-UP)

CS-533C (S/N: 2XN1-UP)

CS-563 (S/N: 8XF1-UP; 7GG1-UP)

CS-583 (S/N: 1EL1-UP)

Track-Type Loader:

963B (S/N: 9BL1-UP)

Track-Type Tractor:

D11N (S/N: 74Z1-UP)

D6M (S/N: 4GS1-UP)

D9R (S/N: 7TL1-UP)

Wheel Loader:

910F (S/N: 1SF1-UP; 1YK1-UP)

924F (S/N: 6MN1-UP)

928F (S/N: 2XL1-UP)

950 Series II (S/N: 4DJ1-UP)

950F (S/N: 7ZF1-UP; 6YG1-UP)

966F (S/N: 7HL1-UP)

Generater Set Engine:

3116 (S/N: 1NJ1-UP)

Industrial Engine:

3116 (S/N: 4PG1-UP)

On-Highway Engine:

3116 (S/N: 9GK1-UP)

Engine:

3116 (S/N: 2SG1-UP; 2WG1-UP; 4KG1-UP; 2BK1-UP)

Introduction

Do not perform any procedure in this Special Instruction until you read this information and you understand this information. This Special Instruction provides troubleshooting procedures for engines that have Mechanical Unit Injectors (MUI) that are having the following issues.

• Misfire

• Low Power

• Hard Starting

Note: The following Special Instruction covers misfires, low power, and hard starting symptoms. This document is not intended to serve as an all-inclusive Troubleshooting Guide, but rather as a supplement to the current Service Manual.

Instructions

1. Use the Customer Interview on the next page as a guide to determine the Customer's Complaint. Determine the symptoms present and the conditions at which the symptoms occur. Encourage the customer to be specific.

2. Investigate and inquire about recent repairs to the engine. A previous repair could be related to the current problem.

3. Verify the Customer's Complaint. If possible, repeat the conditions that are causing the problem.

4. Based on the symptoms and previous engine repairs, find the cause for the complaint using the Misfire, Low Power, and Hard Starting flowcharts. Consider the probable causes in the order they are listed. Avoid pre-conceived ideas.

5. For Fuel System causes, find the corresponding Fuel System Tests in the back of this manual and follow the Tests step by step. When a test procedure is completed but the problem is not solved, move on to the next test on the flowchart.

Note: For Fuel Injector Timing and Synchronization Procedures, refer to the engine's Service Manual.

Customer Interview

Misfire Complaints (Rough Running, Missing, Skipping, Fuel Knock, Hunt, Surge, and Flutter)

Table 1

1. Is Misfire present? (check all that apply):
_____	Under Load?
_____	With No Load (Free Running)?
_____	At Low Idle?
_____	At High Idle?
_____	Only when the engine is warm?
Description of Problem:
_______________________________________________________________________
_______________________________________________________________________
2. List any recent repairs or modifications that could affect the current problem:
_______________________________________________________________________
_______________________________________________________________________
3. Has the Misfire problem:
_____	Developed Gradually?
_____	Developed Suddenly?
_____	Been present since purchase?

Low Power (Slow Response, Poor Accelecration, Won't Pull Load, Track Stall, and Bucket Stall)

Table 2

1. Is Low Power experienced:
_____	Under Load?
_____	Only During Acceleration or Load Change (Poor Response)?
Description of Problem:
_______________________________________________________________________
_______________________________________________________________________
2. Is too much exhaust smoke seen in addition to Low Power?
_____	Yes
If Yes	________Black Smoke? ________ White Smoke?
_____	No
_______________________________________________________________________
_______________________________________________________________________
3. List any recent repairs or modifications that could affect the current problem:
_______________________________________________________________________
_______________________________________________________________________
4. Has the Low Power problem:
_____	Developed Gradually?
_____	Developed Suddenly?
_____	Been Present since Purchase?

Hard to Start or will not Start

Table 3

1. Is the engine Hard to Start (Check all that apply):
_____	After a hot shutdown (30 minutes or less)?
_____	After an extended shutdown (30 minutes or more)?
_____	All the time?
_____	Only in cold ambient temperatures?
Description of Problem:
_______________________________________________________________________
_______________________________________________________________________
2. List any recent repairs or modifications that could affect the current problem:
_______________________________________________________________________
_______________________________________________________________________
3. Has the Hard Starting problem:
_____	Developed Gradually?
_____	Developed Suddenly?
_____	Been Present since Purchase?

Misfire (Rough Running, Missing, Skipping, Fuel Knock, Hunt, Surge, Flutter)

Illustration 1	g01411815
Flowchart for Misfire (Rough Running, Missing, Skipping, Fuel Knock, Hunt, Surge, Flutter)

Low Power (Slow Response, Poor Accelecration, Won't Pull Load, Track Stall, and Bucket Stall)

Illustration 2	g01455800
Illustration 1 - Flowchart for Low Power (Slow Response, Poor Accelecration, Won't Pull Load, Track Stall, and Bucket Stall)

Illustration 3	g01455802
Illustration 2 - Flowchart for Low Power (Slow Response, Poor Accelecration, Won't Pull Load, Track Stall, and Bucket Stall)

Hard to Start or Will Not Start

Illustration 4	g01411879
Flowchart for Hard to Start or Will Not Start

Fuel System Diagnostic Tests

The following tests are diagnostic tests that are used to isolate the issue with either a misfiring injector, a low power engine, or a hard starting engine.

A. Fuel Linkage Binding Test

B. Fuel Injector Preliminary Test

C. Fuel Injector Misfire Test

D. Governor Instability Test

E. Fuel Quality Test

F. Air in Fuel Test

G. Fuel Injector Cranking Test

H. Fuel Shutoff Solenoid Test

I. Fuel Ratio Control (FRC) Setting Test

J. Governor Servo Retaining Ring Test

K. Fuel Transfer Pump Test

L. Fuel Ratio Control (FRC) Diaphragm Leak Test

Fuel Linkage Binding Test (Test A)

Note: Do not run the engine during this test.

Note: The fuel linkage binding test checks for binding in the governor, injector rack, and the control linkage.

Illustration 5	g01422811
(1) Paddle

Illustration 6	g01411905
(2) Injector Rack

Note: Refer to Illustration 6 for the location of the injector rack on the fuel injector.

Illustration 7	g01411915
(3) Mounting brackets for the fuel injectors

Note: Refer to Illustration 7 for the location of the mounting brackets for the fuel injectors.

Illustration 8	g01455803
Illustration 1 - Flowchart for Fuel Linkage Binding Test (Test A)

Illustration 9	g01455806
Illustration 2 - Flowchart for Fuel Linkage Binding Test (Test A)

Fuel Injector Preliminary Test (Test B)

Note: The Fuel Injector Preliminary Test is a visual inspection of the fuel injectors and the rocker arm assembly.

Illustration 10	g01412186
(1) Follower (2) Thrust Plate

Note: Refer to Illustration 10 for the location of the follower and the thrust plate.

Illustration 11	g01412043
Flowchart for the Fuel Injector Preliminary Test (Test B)

Fuel Injector Misfire Test (Test C)

Note: The fuel injector misfire test assists in identifying a cylinder with a misfiring injector.

Illustration 12	g01412188

Illustration 12 shows the direction the rack moves when the fuel injector is receiving fuel.

Illustration 13	g01412058
Flowchart for the Fuel Injector Misfire Test (Test C)

Governor Instability Test (Test D)

Note: The governor instability test checks for the misfires due to governor instability.

Illustration 14	g01422813
(1) Dashpot orifice

Illustration 15	g01422815
(2) Bumper Spring Adjustment Screw

Illustration 16	g01422817
(3) Low Idle shims

Illustration 17	g01422820
Paddle assembly with the bias spring

Illustration 18	g01455808
Illustration 1 - Flowchart for the Governor Instability Test (Test D)

Illustration 19	g01455809
Illustration 2 - Flowchart for the Governor Instability Test (Test D)

Fuel Quality Test (Test E)

Note: The Fuel Quality Test check for fuel quality problems. For more information, refer to Applied Failure Analysis, SEBD0717, "Diesel Fuels and Your Engine".

Illustration 20	g01412094
Flowchart for the Fuel Quality Test (Test E)

Air in Fuel Test (Test F)

Note: The air in fuel test is to check for air in the fuel. This test is also for correcting the air in fuel issue.

Illustration 21	g01412188

Illustration 21 shows the direction the rack moves when the fuel injector is receiving fuel.

Illustration 22	g01455811
Illustration 1 - Flowchart for the Air in Fuel Test (Test F)

Illustration 23	g01455812
Illustration 2 - Flowchart for the Air in Fuel Test (Test F)

Fuel Injector Cranking Test (Test G)

Note: The fuel injector cranking test checks for worn out injectors by measuring the cranking rack.

Illustration 24	g01412134
(3) The rack control (4) The number one fuel injector

Note: Refer to Illustration 24 for the location of the rack control and the location of the number one injector.

Illustration 25	g01412115
Flowchart for the Fuel Injector Cranking Test (Test G)

Fuel Shutoff Solenoid Test (Test H)

Note: The fuel shutoff solenoid test determines if the fuel shutoff solenoid and wiring harness are operating properly.

Illustration 26	g01412143
Flowchart for the Fuel Shutoff Solenoid Test (Test H)

Fuel Ratio Control (FRC) Setting Test (Test I)

Note: The FRC setting test checks the FRC setting.

Illustration 27	g01412145
Flowchart for the Fuel Ratio Control (FRC) Setting Test (Test I)

Governor Servo Retaining Ring Test (Test J)

Note: Do not run the engine during this test.

Note: The governor servo retaining ring test checks for faulty internal parts of the governor.

Illustration 28	g01422811
(1) Paddle

Illustration 29	g01422821
(2) Clevis pin

Illustration 30	g01412147
Flowchart for the Governor Servo Retaining Ring Test (Test J)

Fuel Transfer Pump Test (Test K)

Note: The fuel transfer pump test is a visual inspection of the fuel transfer pump components.

Illustration 31	g01412150
(1) Screen (2) Inlet check valve (3) Spring (4) Bolt (5) Piston (6) Outlet check valve (7) Freeze plug (8) Piston check valve (9) Passage (10) Tappet Assembly (11) Cam

Note: Refer to Illustration 31 for the location of the components for the fuel transfer pump.

Illustration 32	g01412149
Flowchart for the Fuel Transfer Pump Test (Test K)

Fuel Ratio Control (FRC) Diaphragm Leak Test (Test L)

Note: The FRC diaphragm leak test checks for a leaking FRC diaphragm.

Illustration 33	g01412154
Flowchart for the Fuel Ratio Control (FRC) Diaphragm Leak Test (Test L)